keith



N. S. KEITH.

ELECTRIC LIGHT.

No. 246,517. Patented Aug; 30,1881.

UNITED STATES PATENT OFFICE.

NATHANIEL S. KEITH, OF NEW YORK, N. Y., ASSIGNOR TO THE FULLERELECTRICAL COMPANY, OF SAME PLACE.

ELECTRIC LIGHT.

SPECIFICATION forming part of Letters Patent No. 246,517, dated August30, 1881.

Application filed December 2, 1878. D

To all whom it may concern Be it known that I, NATHANIE SHEPARD KEITH,of the city, county, and State of New York, have made a new and usefulinvention for the improvement of Electric Lights, of which the followingis a specification.

Prior to myinvention there were two systems of producing electriclights. One was operated by causing an electric current to pervade thespace between the ends of two solid electrodes of carbon, the electricaction forming the light by heating to a high degree the atoms of carboncarried across the space from the positive to the negative electrode.The other was operated by causing an electric cur rent to pervade astrip of metal or carbon which connected the electrodes, but which wasmade small enough for the electric current to heat it as highly aspossible without fusing or vaporizing it. There are variousmodifications of the two systems, such as placing the electrodes in avacuum or in gases which are not supporters of combustion, but theprinciple modifications have been and are mechanical.

My invention is intended to be used in addition to and in conjunctionwith these two systems, and the only resemblanceitbears to others is inthe fact that I use vapors and gases, but of an entirely differentcharacter and in a different manner. While in these other modificationsnon-combustible gases are used in airtightglasses without renewal,I usecombustible gases and vapors which are continually supplied, not onlyfor combustion but also in such properly-regulated quantities as tocover the electric burner with a deposit of carbon, thus protecting itfrom oxidation, the amount of deposit being controlled so as tofurtherproperly compensate for the waste caused by electric action. In bothsystems the carbon used is gradually oxidized and carried 01f ascarbonic-acid gas by combination with the air admitted to contact withit, or, if in vacuum or gases, is gradually vaporized. \V hen platinumand the like refractory metals are used they are either graduallydisintegrated or melted and vaporized at some time when too strong acurrent of electricity is used.

My invention overcomes these defects, as by it the heated substances areexposed to vapors or gases, such as illuminating-gas and gases andvapors from other hydrocarbons, such as naphtha, benzine, kerosene, andoils, during which exposure carbon is set free in such manner as toprotect the heated substances from contact with air and is itself burnedcontinuously. This decomposition of hydrocarbon vapors and gases takesplace when they are highly heated say to a bright red heat and above-aportion of the carbon constituentbeing freed. If properly-heatedsubstances be exposed to such vapors or gases they become covered with adeposit of carbon, and it very highly heated the deposit assumes thatform of carbon which is called graphite.

I have found, in actual practice with electriclights, that when theheated electrodes and the heated substances composing them or connectingthem are in contact with hydrocarbon vapors or gases they become coveredwith a deposit of carbon, which protects them from oxidation orcombustion, as the carbon thus deposited and the gases and vaporsthemselves in bnrningappropriate the oxygen which would otherwisecombine with the carbon of the electrodes. This burning of the vaporsand gases adds to the heat and consequently to the light. As the flow ofvapor or gas may be accurately and automatically regulated, thedeposited carbon may be increased or diminished in amount, so as tocause the unconnected electrodes to grow each toward the other orrecede; and in case of connected electrodes, the size of the connectionmay be increased or diminished by increased or diminished deposit ofcarbon to suit the electriccurrent used. The advantage of this isobvious to the electrician, for as he will see that, in case when bywaste the electrodes become too far apart, an increased flow of gas orvapor will cause them to grow and thus approach each other, or if tooclose a diminished flow will allow them to recede. v He will also seethat, when in case of connected electrodes the connection getsoverheated, an increased flow of gas or vapor will both increase itssize and conductivity by reason of the deposit of carbon which. takesplace on it, and when too large, a diminished flow of gas or vapor willallow it to diminish in size by oxidation of the deposited carbon sothat in both these cases the changes in the current of electricitycaused by the changes in electrical resistance which result from thesechanges in size and form of the electrodes and connections will operatean automatic electro-magnetic regulator placed in the electric circuitfor the purpose of controlling the supply of gas or vapor.

In putting my invention into practice I have used various forms ofapparatus, some ofwhich, for sake of illustration, I will proceed todescribe. Reference is made to the accompanying drawings, like lettersin all referring to like parts.

A and B are the electrodes. is the tube or conductor for the gases orvapors. D is the place of light, the electric-1i ght are, where the gasor vapor is decomposed. E is a continua tion and enlargement of thegas-tube for inclosing the electrodes in Figs. 2 and 5. F is a glasstube or chimney for inclosing the electrodes in Figs. 3, 7, and S.

The vapor or gas passes through a tubula ture in one of the electrodesin Fig.1. The electrodes may touch each other in some cases, such aswhen it is desirable to produce the light by incandescence of one of theelectrodes in the neighborhood ot'thejunction, as in Fig. 2, and insimilar cases where the electrodes are joined at 1) by small strips,pencils, or wires of the same or other material, as in Figs. 3, 7, and8. The electrodes in Fig. 5 should be revolved, the axis being thecenter line of their length. Each of these devices has the flow of gasor vapor regulated by a stopcock or valve, which is opened and closedautomatically by an electro magnetic movement placed in the electriccircuitused for the light. This is is closed.

a current either partially or wholly closes the stop-cock, so that theflow of gas or vapor is regulated to suit the current of electricitypervading the electric-light are.

Figs. 9 and 10 show two views of an automatic device for controlling theflow of the gas or vapor.

M is an axial magnet, the coils of which are in the circuit of which thelight-arc is a part. The core N moves up or down in obedience to changesin the current caused by variations in theresistance of thelight-arc inthe well-known manner. The spring 0 serves to adjust this motion to therequirements of the case. When no current exists the spring pulls thelever P upward and closes the passage through the cock R, so that no gasor vapor can flow. A current causes a downward movement of the core N bymagnetic attraction, opens the passage, and allows the flow of gas orvapor. Too strong a current, such as would be caused by too low aresistance at the light-arc, pulls the core and lever far enough toclose the passage and stop the flow of gas or vapor.

I claim- The mode of protecting electrodes and materials used in theelectric-light are from oxi' dation or combustion by providing othercoinbustible material thereat, and by changing the size and electricresistance thereof, the same consisting in conjoining properly-regulatedquantities of one or more hydrocarbon "apors or gases with the heatedelectrodes and materials, so that by the reactions wh ich take placecarbon is freed and part thereof is deposited upon the heated electrodesand materials.

N. S. KEITH.

Witnesses:

WELLs D. WALBRIDGE, W. HART SMITH.

